We attempted to induce corneal flattening in a baboon model by implanting donut-shaped hydrogel lenses in an intralamellar pocket created by a microkeratome. 7mm diameter hydrogels in five eyes produced corneal steepening from 3.4 to 22.5 diopters. Three to five months postoperatively the study was terminated and the corneas studied with correlative microscopy. There was an absence of inflammation, but the intralamellar pocket was lined with keratocytes, focal areas of epithelial implantation were found and the overlying corneal cap was normal.